This invention relates generally to fluid administration sets and specifically to inlet blood filter assemblies. Inlet blood filter assemblies are used in the administration of blood into a patient. These assemblies function as the inlet end of various blood, and other fluid administration sets.
Typical inlet assemblies include a spike, drip chamber, pump chamber and filter member. The flow of fluid or blood is from the spike, through the drip chamber and pump chamber and then into the filter chamber. In the filter chamber large particulate is removed. The filter chamber is especially important when blood is being administered as whole blood tends to coagulate and therefore contains clots which must be filtered out. After the fluid has been filtered it exits the inlet filter assembly and enters an administration set tubing where it is administered into a patient.
Inlet blood filter assemblies are equipped with a pump chamber so that the flow rate of the fluid through the inlet filter assembly may be increased. Typically, it is necessary to administer fluid faster than the normal gravity pressure. This is especially true in trauma patients who have experienced great losses of blood. These pump chambers are especially useful in view of the fact that whole blood is stored in a cold environment thus decreasing its fluid flow rate. By compressing the pump chamber the fluid is forced through the inlet blood filter assembly.
In spite of the need to increase the fluid flow rate in trauma patients the use of the pump chamber suffers a major drawback. Because the pump chamber is located above (upstream from) the filter chamber, the utilization of the pump chamber to increase the fluid flow rate, sacrifices the efficiency of the filter. The efficiency of a filter is inversely proportional to the fluid pressure of the fluid to be filtered. When the pump chamber is compressed small clots of blood are forced through the filter into the patient. There has therefore been an unsolved need for an inlet blood filter assembly construction wherein the compression of the pump chamber did not sacrifice the filters efficiency.
Typically, these inlet blood filter assemblies are constructed from a straight piece of extruded tubing which is deformed through RF heating and pressure around the various other component pieces to form sealed joints and/or chambers. These joints and chambers are usually done one at a time and in some cases require the addition of a filler sleeve to obtain a suitable bond. Because of this construction these inlet blood filter assemblies are of a uniform thickness, i.e., the walls of the drip and pump chambers have the same thickness.
Because a very necessary feature of the pump chamber is flexibility it is desirous to create a pump chamber with thin walls. Due to the fact that these assemblies are typically a straight piece of extruded tubing the thinning of the walls of the pump chamber would also thin the walls of the remaining portions of the inlet blood filter assembly. This has thus prohibited an inlet blood filter with a pump chamber with thin walls. Thus, there has been an unsolved need for an inlet blood filter assembly unit with a flexible thin walled pump chamber.